The present invention relates to a transport device for piece goods or the like, of the type comprising rolling members which support the piece goods, a plate member having holes positioning rolling members with their tops protruding above the top of the plate member and in linear rows transverse to the direction of transport, and rolling drive devices below the plate member and supporting the rolling members.
Such a prior transport device is known from Federal Republic of Germany AS No. 22 61 936; which discloses a conveyor-path switch for transferring piece goods from a first conveyor onto at least one second conveyor which travels in a direction different from that of the first conveyor. In such conveyor-path switches it is important to be able to change the direction of conveyance of the piece goods. This requires complicated drive devices for the rolling members (balls). For this purpose, the individual drive devices consist of drive disks which are rotatable parallel to the surface of conveyance and on which one of the rolling members rests eccentrically at all times, all the drive disks being arranged for rotation on a common mounting plate. The plate, which has passage openings for holding the rolling members, is arranged fixed in space. By displacing the mounting plate with respect to the upper plate which holds the balls, the direction of conveyance of the rolling members can be varied within wide ranges.
This known conveyor-path switch is too expensive to be used as a linearly conveying transport device. It is therefore used only as a short transfer deck.
For linearly conveying transport devices two other systems have been used up to now. In one of these, there are roller tables which are arranged displaceable vertically, below an upper plate, arranged fixed in space, having passage openings for the individual rollers. In the lowered condition of the roller table, the top side of the upper plate can be driven over by vehicles such as fork trucks, hand elevating trucks or the like, without the individual rollers of the roller trains being overloaded by spot loading from the wheels of the vehicle. However, with this transport system, the drive of the individual rollers, which are seated on shafts, is cumbersome and is made additionally difficult by the lift device. Furthermore, the cutouts in the surface of the upper plate, which are open in the lowered condition of the roller table, represent a place of danger, in addition to which dirt and larger particles can enter into these openings when the rollers are lowered, thus impairing the operation of the lift device as well as the rollers themselves.
In the other of these known linear transport systems, so-called "pull carpets", driven by guide drums, are pulled over a slide surface. Very high frictional forces are present between the carpet and the slide surface, which forces make high drive powers necessary and are responsible for rapid wear of the carpet material. Furthermore, the carpet material does not withstand partial loadings resulting, in particular, from sharp edges on the piece goods.